Particulate filters (PFs) are designed to accumulate exhaust particulates (“soot”) and are used in a variety of applications, including diesel and gasoline engined motor vehicles. PFs are ceramic-based structures that generally comprise a network of interconnected web walls that form a matrix of elongate, gas-conducting cells having a variety of cross-sectional shapes.
The performance of a PF depends in part on the amount of particulates it accumulates. A PF can be “regenerated” via thermal processing once the amount of accumulated particulates reaches a certain level. The success of the regeneration process, however, requires accurately determining the amount of accumulated particulates.
Present methods of determining particulate accumulation tend to be rather inaccurate because they rely on filter performance parameters a complex algorithm based on filter pressure drop values and engine operating parameters (time, speed, torque etc.). Often, the pressure drop values lead to either an under or over prediction of the amount of particulate matter accumulated in the DPF.
Knowing the precise amount of particulates in a particulate filter (for example, soot in a diesel particulate filter (a “DPF”)) over a wide range of load levels allows for proper implementation of regeneration processes and increases filter durability. In addition, the efficiency of the current particulate or soot estimation methods would be significantly improved if low particulate or soot levels can be accurately measured.
What are needed therefore are methods for more accurately determining the amount of accumulated particulates for example soot in a PF.